Belt drier heated by radiation



March 29, 1955 A. HALTMElE R 2,705,137

BELT DRIER HEATED BY RADIATION Filed Dec. 13, 1950 2 Sheets-Sheet l mmvroa ALFRED HALTMEIER (Ruiz: his ATTO NE YS BELT DRIER HEATED BY RADIATION Filed Dec. 13, 1950 2 Sheets-Sheet 2 l EH I JNVENTOR. 4 ALFRED HALTME/ER hi AT T ORNE Y8 United States Patent Ce 2,705,131

Patented Mar. 29, 1955 which are principally responsible for the temperatures 2 705 137 acting on the control devices arranged in that section.

v The radiating surfaces are preferably mounted in form BE RI HEATED BY RADIATION of pipes lying above the belt drier to carry alternately hot 5 and cool gases. For reducing the heat stresses, these Alfred Haltmeier, Leverkusen-Bayerwerk, Germany, asalternately heated and cooled pipes may be extended slgnor to Farbenfabriken Bayer Aktiengesellschaft, through the wall of the drying chamber so as to project Leverkusen, Germany, a corporation of Germany outwardly. This may be achieved by means of elastic expansion compensators, for instance, expansion pipes. Appheatlon December 1950 Sena! 200,519 For increasing the elastic'ty the radiating pipes may be Cl priority, application Ge y December 16, 1949 E-shaped or may be installed in form of a plain coil.

4 Claims, (CL 3 13 tected from the radiant heat by means of protective screens, for instance, aluminum sheets. Furthermore, it 1' isofadvantaeta tea't' i o The present mventron relates to belt driers heated by 0 the belt O flange h r dla mg ppes parallel I When the pipes carrying the source of radiant energy are arranged closely side by side it is advisable to unite in a flat box, preferably provided with bars between the radiating pipes. If these bars are fixed to one of the walls eenduetmg thebelt along. radlatmg surfaeesof the box, the box is protected from being compressed a 10114015 drymg a hltherto Surpnsmgly by the external atmospheric pressure without affecting mm extenswe Thls.may be due to the i the elasticity desired to take care of thermal expansion. cultles encountered in attempting to adequately ad ust the amount of radiant heat with varying quantities and/or \Larynlg moisture contents of the material distributed on t e e t.

According to the present invention these difliculties are overcome by correlating the rate at which the wet 30 material is fed to the vacuum chamber with the speed of the beltdrien e Preferably accqmplished by pose, throttling or closing devices may be provided in means of pipes filled With wet material, said pipes conthe fuel supply e pipes, operation of whlch is started by Fleeting the drying. chamber Wlth an outside tank column the radiation guarded temperature control devices.- By closing a membrane valve which may be installed-in one of the fuel supply pipes, the gas supply Eis cut off and cool air is sent through the pipe in place of the hot combustion gases; on opening the membrane valve, the flow of gas is resumed and, on ignition by a pilot flame, again supplies heat for the drying operation.

A selectively absorbing layer may be formed as a result of the initial evaporation of moisture from the material coming out of the pipes. When thetemperatures within the drying chamber exceed adjustable limits, the heating through said pipes is correlated with the speed of the belt drier. For this purpose, in the pipes feeding the wet material transporters, gear driven pumps, rotating worms, etc. may be used,the driving gears of which are coupled with the driving gear of the belt. In order to 40 prevent air from entering these pipes the passages for the ing process, means such as a speed ventilator may be provided for rapid removal of this layer. It is advisable to remove the vapors in the opposite direction to that of the motion of the belt. When corroding vapors are formed in the drying process, it is of advantage to employ corrosion-resistant jet blowers.

The accompanying drawings illustrate .,some possible modes of execution of the present invention by way of example. e

In these drawings Fig. 1A diagrammatically indicates a side sectional view of another drier built in accordance terial to be dried emerges at the rate of the velocity of the belt. Means may be provided to prevent clogging of the slit (e. g., vibratory means) and to supply a uniform amount of material for drying (e. g., pressure means).

Variations in feed resulting from variation of thle fiffih f iii. 5 123151 5 35 552533 s ii 'iiii ii in; gjf g invemwnfiaken alqng i 2- 1 f i drying process. For example, when the radiating sur- 3 A g g gg i i ig? 2 $2 5 5 faces are electrically heated, control means of the heatlines in Fig 2A tit are,srftstasssi tsrf nauseatin g a shgws g ge -g a e in the for example, by means of a controller cylinder connected a lrymg er lumera deslgnates a with to the driving gear of the belt drier. When heating with 5 conflmt or i gases from the vacupm gaseous, liquid or powdered fuel apportioning devices E; 3 5 fig i g ff ffgg i l g gf g gg coupled with the driving gear of the belt drier are adp g vantageously arranged in the fuel supply pipes. These fi g t m gi ifi i? 23 fi g apportioning devices may be, for instance, apportioning g .Y f eg i, 0 e drums, bucket wheels, rotary blast apparatus, pumps or e {Ivmg s a e e Immerse m worms the tank 7. The axls 9 of the shaft 8 18 extended In addition to the above-described control devices, through the stufiing box the t to the dnve means must also be provided to accurately control the (not e matenal. to be .dneq conveyed on radiation emitted from the radiating surfaces in such a e 1 e f g the dlrectlon of the arrowmanner that the dried material has the desired final moism lrradlated, the drylng Zone means ture content. For this purpose devices may be installed the q g tubes: hcated by combustion gases, which automatically h off the h i i sections f said radiatlng tubes being installed in some distance above the radiating surfaces when temperatures in these secand P 'Q t0 the movlllg dlrect'lon 9 the belt 1 tions within the drying chamber exceed adjustable limits. combllstlofl gases 1 1 th dlrectlon of the belt 1 This may be effected by temperature control devices ar- The radlatlllg tubes are P For l'educlng the ranged at radiation guarded sections within the drying heat stresses the radiating tubes 11' are extended through chamber, for instance, above or beneath the travelling the wall of the vacuum chamber 2' so as to pro ect outbelt. It is of advantage to shut oil", in the first line, those wardly. The parts of radiat ng tubes 11' pro ecting outsections of the heating appliance of the radiating surfaces wardly are surrounded by wider tubes 12'. One end of the pipes leading through the wall of the drying chamber.

.Thus heating is followed by cooling in turns.

the wider tubes 12' is fastened to said 11', the other end of the wider tubes 12' the vacuum chamber 2'.

Hot combustion gases or cooling air respectively flow through the radiating tubes 11. For this purpose there are provided gas flames 1.3 installed at the inlet of the radiating tubes 11. The combustion gases or gas flames 13' are removed by suction devices, for instance, an ejector 14, installed at the outlet of the radiating tubes 11. Radiation guarded spots in the drier at the dry end of the belt 1' are provided with temperature control devices, for instance, resistance thermometer 15', which glide upon the drying surface of the traveling belt 1 and influence other devices, for instance, change-over-switches 16', adapted to adjust the supply of fuel. When the wanted temperature is exceeded the change-over-switches 16' bar the supply of fuel from gas pipe 17 to flame 13, so that the latter extinguishes. The heating of the radiating tube 11 is now cut and the tube is simultaneously changed to cooling, since instead of the combustion gases cooling air is sucked into the radiating tube 11 by means of ejector 14. When the temperature drops again at the control device 14', the gas supply to burner 13' is released again and the gas streaming out is lighted by pilot flame 18'. The radiating tube 11 is now heated again.

Since several radiating tubes are arranged above the belt all over the band-width it is of advantage to provide for changing over each radiating tube ll' separately in order to produce uniform temperatures all over the belt 1. For this purpose each of said radiating tubes 11 is provided with a temperature control device 15 gliding upon the drying surface of the belt 1. Each temperature control device 15' influences a change-over-switch 16'. One pilot flame 18' is provided for each flame 13'. Radiation protective screens 19' and 20 made, for instance, of sheet aluminum, are arranged for reducing the radiation power of the radiation tubes 11' in undesired directions. The dried material drops otf at the roll 21' of the belt 1' into collector 22, from which it is removed from time to time.

The invention may be variously otherwise embodied within the scope of the appended claims.

I claim:

1. Vacuum drying apparatus comprising walls forming a chamber, means for evacuating said chamber, a horizontal belt conveyor in said chamber, means at one end of said chamber for feeding material to the upper run of said belt conveyor, a plurality of heat radiating tubes adapted to be heated by combustion gases, said tubes being positioned above and parallel to the belt in said chamber having inlets and outlets projecting through the top of said chamber, burners positioned adjacent the inlets of said radiating tubes, and means for withdrawing the combustion gases from the outlets of said tubes, said inlets of said radiating tubes being positioned at the inlet side of said chamber above the material feeding the inlets.

2. Vacuum drying apparatus comprising walls forming radiating tubes to the wall of a chamber, means for evacuating said chamber, a horizontal belt conveyor in said chamber, means for feeding material to the upper run of said belt conveyor, a plurality of U-shaped tubes having vertical and horizontal portions, said horizontal portions being spaced above and parallel to the upper run of said belt, the vertical portions of said U-shaped tubes extending through the top wall of said chamber so as to project towards the belt in said drier, said tubes being surrounded by wider tubes, one end of each of said wider tubes being fastened to one of said radiating tubes, the other ends of each of said wider tubes being attached to the wall of the vacuum chamber, burners positioned adjacent the inlets of said Ushaped tubes, and means for withdrawing combustion gases from the outlets of said tubes, said inlets of the radlating tubes being positioned at the inlet side of said chamber above the material feeding the inlets. 3. Vacuum drying apparatus as defined in claim 2, including temperature control means positioned closely adjacent the upper surface of said travelling belt, and means connected to said temperature-control means to adjust the calorific content of the gases passed through said radiating tubes.

4. Vacuum drying apparatus as defined in claim 3 in which a series of said radiating tubes is arranged covering the entire width of said belt.

References Cited in the file of this patent UNITED STATES PATENTS 1,167,029 Stickle Ian. 4, 1916 1,250,496 Passburg Dec. 18, 1917 1,277,895 Foster Sept. 3, 1918 1,358,431 Field Nov. 9, 1920 1,547,156 Loepsinger July 21, 1925 1,580,658 Field Apr. 13, 1926 1,933,819 Miles et al. Nov. 7, 1933 1,988,677 Arnold Ian. 22, 1935 2,047,471 Hepburn et al July 14, 1936 2,132,897 Gentele -2 Oct. 11, 1938 2,235,324 Moreland Mar. 18, 1941 2,349,300 Olsen May 23, 1944 2,391,441 Baer Dec. 25, 1945 2,420,399 New May 13, 1947 2,435,503 Levinson et al. Feb. 3, 1948 2,480,248 Karlsson et al Aug. 30, 1949 2,515,098 Smith, Jr. July 11, 1950 2,528,476 Roos et al. Oct. 31, 1950 2,533,125 Levinson et al. Dec. 5, 1950 FOREIGN PATENTS 883,178 France Mar. 15, 1943 OTHER REFERENCES A Method for the Production of Dry Powdered Orange Juice, by Sluder et al. Food Technology, vol. 1, No. 1, January 1947, pages to 94. 

1. VACUUM DRYING APPARATUS COMPRISING WALLS FORMING A CHAMBER, MEANS FOR EVACUATING SAID CHAMBER, A HORIZONTAL BELT CONVEYOR IN SAID CHAMBER, MEANS AT ONE END OF SAID CHAMBER FOR FEEDING MATERIAL TO THE UPPER RUN OF SAID BELT CONVEYOR, A PLURALITY OF HEAT RADIATING TUBES ADAPTED TO BE HEATED BY COMBUSTION GASES, SAID TUBES BEING ADAPTED TO BE HEATED BY COMBUSTION GASES, SAID TUBES BEING HAVING INLETS AND OUTLETS PROJECTING THROUGH THE TOP OF SAID CHAMBER, BURNERS POSITIONED ADJACENT THE INLETS OF SAID RADIATING TUBES, AND MEANS FOR WITHDREAWING THE COMBUSTION GASES FROM THE OUTLETS OF SAID TUBES, SAID INLETS 